Defrost system for self-service refrigerated display cases



B. J. SPENCER Jan. 4, 1966 DEFROST SYSTEM FOR SELF-SERVICE REFRIGERATED DISPLAY CASES 2 Sheets-Sheet 1 Filed Nov. 2, 1964 FlG.l

F I 2 INVENTOR.

BERNARD J. SPENCER BY(M W g Jan. 4, 1966 B. J. SPENCER 3,226,945

DEFROST SYSTEM FOR SELF-SERVICE REFRIGERATED DISPLAY GASES Filed Nov. 2, 1964 2 Sheets-Sheet 2 I N VEN TOR.

9 mm m M M/ @%fl/ H/ I 0 8 I 70 v 0| 0 (2 H I\ h A 3 6 u I3 H H m 9 a F Hi i 3 M W 5 O- V I 9 o. H/ B l4 oo L J WFSQ 3 5 J z I PM ,4 III 85 884 m 092 3 In 9 9 8 II B BERNARD J. SPENCER BY M (M @b United States Patent 3,226,945 DEFRGST SYSTEM FOR SELF-SERVICE REFRIGERATED DESPLAY CASES Bernard .1. Spencer, 45 NE. 212th Terrace, Miami, Fla. Filed Nov. 2, 1964, Ser. No. 408,131 1 Claim. (Cl. 62-256) This invention relates in general to self-service type refrigerated display cases and in more particularity to a defrost system for such cases.

Display cases for frozen and refrigerated foods in use today are generally of the type in which the display space is open for easy access thereto by the customer. The two most common types in use are (1) the open top case where the refrigerated food is located below the top of the case and the customer reaches downinto the case to obtain the desired product, and.(2) the type with an open-top lower compartment to which ahigh back wall containing refrigerated shelves has been added. In this latter type the consumer may obtain the food products by reaching into the lower compartment or from the refrigerated shelves located nearer to the eye level.

In either of these types of display cases they are ordinarily provided With means for circulating refrigerated air across. the food from the rear of the cases to a return air duct near the front of the cases for return of the air to the refrigerating or cooling mechanism. The circulated refrigerated air forms a layer or curtain of cold air over the food so as to prevent the atmospheric air from raising the temperature of the displayed food. The same air is recooled by the refrigerating evaporators usually located below the food and recirculated through the food storage compartment by a fan or fans placed in the path of air flow.

Due to the fact that the cooling air is exposed to the atmosphere as it is circulated through the display area, a considerable amount of moisture is picked up by the air. As the moisturized air passes across and through the evaporators, the moisture will condense on the evaporators and, due to the lowered temperature, cause a frost buildup thereon. This results in the necessity of having to defrost the evaporators at frequent intervals.

The method of defrosting this type of refrigerated display case is to turn off the refrigeration coils while at the same time the circulating fan or fans are permitted to continue running. The same pattern of circulating air, across the displayed food, back through the refrigerating coils and through the circulating fan or fans is continued with the olny difference being that the air is not being cooled by the evaporators.

Some systems contain defrost heater on the forward side of the evaporators which are turned on when the evaporators are turned off.

In each of the systems, those with defrost heaters and those without, defrosting is a time-consuming and sometimes unsatisfactory operation. The air being drawn into the heaters is being drawn from the inside of the display case itself after it has passed over the surface of the refrigerated food. This means that the air is extremely cold, sometimes below 0 F., and it takes an extremely large amount of heat to raise it to a temperature above 32 P. so that it will remove the frost and ice from the evaporators. The amount of heat required is increased appreciably by the fact that the cold air istransient and not immobile during the heating thereof.

Assuming the air is heated sufliciently to defrost the evaporators, this same warmed air is circulated through the display area in contact with the refrigerated food. It will raise the temperature of the food and if the food is frozen many times it will completely thaw it. This constant thawing and refreezing of the food every time the system is defrosted is undesirable as frost will build up on the package making it unattractive to the eye of the consumer. Further, from a health standpoint, continuous thawing and freezing is undesirable as every time it thaws there is a chance that harmful bacteria will become active in the food.

It is a primary object of this invention to provide a defrost system which utilizes atmospheric air in the defrosting cycle so that no defrost heaters are required.

It is a further object of the invention to provide a defrost system in which the defrosting air is discharged to the atmoshere without being circulated through the display area after it has passed through the evaporator-s.

A still further object of the invention is to provide a defrost system which accomplishes the defrosting in a very short period of time so that the temperature of the refrigerated food will not raise appreciably during the defrosting cycle.

Another object of the invention is to provide a defrost system which may be built into a refrigerated display case with a minimum of change in the construction thereof.

Other objects and advantages of the present invention will be apparent from the following description and the accompanying drawings in which:

FIGURE 1 is an elevational view of a typical open top self-service refrigerated display case with my invention installed therein; i

FIGURE 2 is a sectional view taken substantially on the lines 2-2 of FIGURE 1; i

FIGURE 3 is a sectional view through a typical multiple deck refrigerated display case with my new and novel defrost system installed therein; and

FIGURE 4 is a sectional view of a meat display case incorporating my invention therein.

Referring now to FIGURE 1 of the drawings, the display case has a front panel 5, ends 6 and 7, and top or hood 8. Extending along the entire top of the front panel is glass panel 9 through which the customer may view the displayed food.

At the top of front panel 5 are two slotted sections 10 and 11 between which there is a solid section 13. In side section 13 is motor 12 for actuating movable panel 34 (FIG. '2). The numeral 14 indicates the open section of the display case.

Going now to FIGURE 2, behind front panel 5 is insulated front 15, bottom 16, and back 17. Within the confines of 15, 16, 17, and 8 is the food display section comprised of a removable floor 18, a front wall 19 and a rear wall 20.

Beneath floor 18 is located a typical refrigeration system comprised of evaporators 44 and circulating fan 22.

At the lowest point of insulated bottom 16 is drain 23 with its alternate discharges 24 and 25.

The walls and 19 are spaced apart so as to form duct 26. Walls and 17 are spaced apart so as to form duct 27.

Panel 34 is hinged to the bottom of glass panel 9 by hinge 29. As will be noted, panel 34 is of the same insulating material as front 15 and when in its closed position forms an extension thereof. Where panel 34 contacts front 15 a resilient gasket is provided with heating elements 31 therein.

Where panel 34 contacts wall 19 gasket 32, with on closed heating element 33, is provided. Panel 5 has a plurality of openings 10 therein for the entrance of air when panel 34 is in the open position.

In rear wall 17 is opening 35 into which panel or baifle 36 is hinged by hinge 37. Resilient gasket 38, with heating elements 39 therein, is provided for panel 36 to contact in the closed position. Wall 29 is provided with a gasket 40 containing heating element 41.

In the normal operation of the display case batlle 34 would be in a position in contact with gasket 30 and baffle 36 would be in a position in contact with gasket 38. This leaves ducts 246 and 27 relatively free from obstruction. Heating elements 31 and 39 prevent the respective bafiles from adhering to the gaskets due to the cold atmosphere prevailing at these points.

Circulating fan 22 moves air up through duct 27, out through openings 28, across the top of the cabinet in a path shown by the dotted arrows 43. As this air is relatively cold it will remain as a layer as it moves across the top of the displayed food, forming a curtain to prevent the food from becoming warm. The cold air will flow forward and down between glass panels 9 and 42 through duct 26 due to the suction of circulating fan 22. As the air is drawn across evaporators 44 it releases any heat it contains and is recooled so as to be recirculated around the same path again.

When it is necessary to defrost evaporators 44 they are turned off with fan 22 continuing operation. When evaporators 44 are turned off motor 12 will automatically 7 any air which would be drawn from the inside of the display case and well above the temperature which would prevail were this cold air passed over defrost heaters. This provides quicker defrosting of evaporators 4-4. As the defrosting cycle will be of short duration the layer of cold air in the case, due to its extreme coldness, will lay on top of the refrigerated food and protect it from thaw- As soon as evaporators 44 are free of frost the baflles 34 and 36 will move to their outwardmost positions, and evaporators 44 will be turned on. The case is again in normal use as a refrigerated display case.

FIGURE 3 illustrates the application of my new and novel defrost system to a typical multiple deck frozen food or diary display case. The display case has a front panel 45 which has a plurality of openings 46 near the top thereof. Behind panel 45 is insulated wall 47 which, with insulated bottom wall 48, back wall 49, and top 50, form the basic display enclosure. Within the inside, removable bottom 51, front 52, and back 53 form the food containing portion with shelves 54 and 55 providing additional food storage space.

Between walls 47 and 52 is duct 56 which communicates with the space below bottom 51 containing exaporators 57 and fan 59. Between walls 53 and 49 is duct 60 which is also in communication with the space below bottom 51.

Each of shelves 54 and 55 are in open communication with duct 60. Shelf 54 has a plurality of outlets 61 therein whereas shelf 55 has a plurality of outlets 62.

Drain 63, with alternate outlets 64 and 65, is located in the lowermost part of bottom 48.

Wall 47 has a gasket 66 at the top thereof. Heating elements 67, to prevent sticking of panel 68 to gasket 66, are embedded in the gasket. Panel 63 is hinged at 69 to move from open to closed position and i made of the same insulating material as front 47. Wall 52 has gasket 70 with heating element 71 enclosed therein.

In wall 49 opening 72 with suitable outlets 74 is provided with a gasket 75 containing heating elements 76 therein. Wall 53 is provided with gasket 77 having heating element 78 therein. Panel 79 is pivotable between gaskets 77 and 75 by means of hinge 80.

In the normal operation of this type of display case, air is drawn by fan 59 across evaporators 57, through fan 59 and forced upwardly through duct 60. Panel 79 is in a position tightly against gasket therefore duct 60 is unobstructed at this point. The cooled air travels upwardly with some of it going out through the outlets 61 in shelf 54, some of it going out through the outlets 62 in shelf 55 and some of it going out through outlets 81 at the top of the display case following the path of dotted arrows 82.

The cooled air, due to its density, will cascade downwardly across and over the displayed food and is drawn into duct 56 through openings 73 in the top thereof. Panel 68 will be tightly against gasket 66 therefore the duct 56 is unobstructed. The air will be drawn through the duct 56 to the evaporators 57 to be recooled and recirculated by fan 59.

To defrost the evaporators 57 they are turned off with fan 59 continuing operation. At the same time panels 68 and 69 are moved by suitable motors to the position shown in FIGURE 3. Atmospheric air is drawn in through openings 46, through duct 55, across exaporators 57, through fan 59, up through duct 60, and out through outlets 74 in opening 72. During the short defrosting period the cold air within the display cabinet will form a layer to protect the food from warming up.

FIGURE 4 illustrates a typical meat display case with my novel defrost system installed therein. In a meat display case the temperature is maintained at a figure much higher than in a frozen food display case. A common frozen food display temperature is 0 F. while 32 F. is a common temperature for a meat case.

Front panel 84 covers insulated front 85 which has an opening 89 near the top thereof. Panel 84 has a plurality of openings 90 therein where it is in communication with opening 89. Glass panel 88 is provided for easy viewing as is glass panel 98 on the top of wall 97.

Bafile 91 is hinged by hinge 104 so as to permit movement of the baffle between gasket 92 containing heating element 93 and gasket 94 containing heating element 95.

Rear wall 37 has an opening 102 therein with a plurality of outlets 103. Baffie 106 is hinged at to permit movement between gasket 107 with heating element 108 and gasket 109 with heating element 110.

The meat-holding compartment has a removable bottom 96 with a front wall 97 and a rear wall 99. Openings 100 are near the top of wall 99.

Beneath bottom 96 are evaporators 111 and circulating fan 112.

A second bottom 113 is provided below the cooling mechanism. This provides a cooled storage space 114 between the cooling mechanism and the insulated bottom 86. Drain 115 connects the two compartments and drain 116 is connected to alternate outlets 117 and 118 as is typical in the art.

It will be noted that baffles 91 and 106 of this embodiment are not made of thick insulating material. In a meat case the temperature of the air travelling in ducts 121 and 122 is not as low as in a frozen food case therefore any heat transmitted through the baffles 91 and 106 is not as harmful as in the instance of a frozen food case. In the frozen food cases it is important to insulate against all possibility of heat raising the temperature of the circulatmg air.

However, if desired, bafiles such as 91 and 106 may be used in any of the embodiments shown and described and, likewise, insulated panels may be used instead of baffles in the embodiment shown in FIGURE 4.

Operation of the defrost system in this embodiment is substantially the same as in the previous embodiments therefore, for the sake of brevity, a detailed description will not be given.

In each of the systems shown and described, the atmospheric air is shown as drawn in near the top front of the case and discharged out the back of the case. It is within the purview of this specification to bring the air in at any level desired, for example at floor level, and to discharge it at any desired level, again, for example, at floor level.

The locations of the inlets and outlets are not considered critical, the important fact being that the defrosting air is not circulated over the displayed food.

Although I have shown only three embodiments of my invention, it is understood that it is not intended to be exhaustive nor limiting of the invention, but on the contrary, is given for purpose of illustration in order that others skilled in the art may fully understand the invention and the principles thereof, and the manner of applying it in practical use so that they may modify and adapt it in various forms, each as may be best suited to the conditions of a particular use, and still be within the scope of my invention.

What is claimed is:

In a self-service refrigerated display case having a front wall, a bottom, a back wall, a top, and a cooling mechanism within the case,

(a) an opening in said case for providing access to a display space,

(b) means for circulating air across the cooling mechanism,

(c) a first duct connected to said circulating means and to a discharge opening in the display space,

(d) a second duct in communication with said first duct between the circulating means and the discharge opening,

(e) means for selectively opening either the first duct or the second duct,

(f) a third duct adjacent the front wall of said case,

(g) said third duct opening into the display area adjacent the top of said front wall,

(h) said third duct being in communication with the cooling mechanism,

(i) a fourth duct in communication with said third duct at a location between the opening into the display area and the cooling mechanism, and

(j) means for selectively opening either the third duct or the fourth duct,

(k) a resilient gasket located in said second duct,

(1) a heating element enclosed within said gasket,

(m) a second resilient gasket located in said fourth duct,

(n) a heating element enclosed within said second resilient gasket,

(0) said first resilient gasket located so as to contact the means for selectively opening either the first or the second duct when said first duct is open, and

(p) said second resilient gasket located so as to contact the means for selectively opening either the third duct or the fourth duct when said third duct is open.

References Cited by the Examiner UNITED STATES PATENTS 2,124,268 7/1938 Williams -1 62-276 3,082,612 3/1963 Beckwith 62256 3,091,942 6/1963 Dickson 62256 3,094,851 6/1963 Beckwith 62-256 3,122,892 3/1964 Beckwith 62256 30 WILLIAM J. WYE, Primary Examiner. 

